This past Saturday I received a new Marshall DSL40C, Line 6 M13 and VooDoo Lab Control Switcher so the M13 can change channels/reverb on the amp. Played the amp w/the M13 Saturday and no issues. Even at loud volumes the amp was relatively quiet.

Saturday night I setup the Control Switcher and was able to successfully change channels on the amp when using the M13 Latch Scene mode. It was late so volume was low and I did not test the reverb.

Sunday (yesterday) I played at loud volume again and the hiss on the gain channel was horrible. Anything past 4-5 on Lead 1 was incredibly noisy. Lead 2 is un-usable. Also, discovered that the reverb no longer works on either channel (it was working on Saturday). I did try resetting the tubes thinking maybe one came loose during shipping but that made no difference.

Sweetwater is replacing amp so that's good. My concern is what caused the amp to fail and the only difference between Saturday and Sunday was adding the Control Switcher into the signal chain. It's a pretty simple device so logically I don't see how that could affect it, but I have to admit I'm concerned about trying it with the new amp.

Have there been any reported issues with the Control Switcher and/or is there something I should or should not be doing when I set it up? Is there a way to test signal voltage, etc? As far as setting it up I changed the configuration to accept both PC and CC signals, connected the MIDI cable from the M13 to the Control Switcher and connected the Insert cable from the Control Switcher to the amp footswitch jack. It's really impossible to mess that up.

I noticed that on some of the Youtube Videos showing the Control Switcher that when they press buttons 1 & 4 to save the configuration all four lights flash at the same time. When I press buttons 1 & 4 to save on my device, lights 1 & 3 and 2 & 4 alternately flash - not all four at the same time. The manual only states that "the LED's will blink to confirm that you saved the preset."

We have never heard of a case where a Control Switcher caused damage to any amplifier. I would connect to the replacement amp with no fear.
But, what happened? On this amp we would only be making or breaking a connection to ground as the amp footswitch circuit intends. If something were really wrong with the connections you could possibly have strange things happen when everything is hooked up, but I would expect any odd behavior to stop once things were disconnected.

As for the lights when saving, I'm going to guess that you have the newer Control Switcher with the red buttons and the videos were likely the older model version with the black buttons?
The Red Button model does do the alternating LED flash to confirm a successful save.

Thank you, John, for your prompt reply - I greatly appreciate it! When the new amp arrives later this week I'm going to play it straight up for a few days to make sure it's all good. I'll then add the M13 and Control Switcher back in the mix and I suspect I'll be good to go. Good to know about the flashing lights too!